This application claims the priority of British Application No. 0118239.3 filed Jul. 26, 2001, the disclosure of which is being incorporated herein by reference.
The present invention relates to an air-bag arrangement, and more particularly relates to an air-bag arrangement for use in a motor vehicle in the form of a so-called xe2x80x9cinflatable curtainxe2x80x9d.
An inflatable curtain is an air-bag or inflatable element which is initially mounted in the roof of a motor vehicle adjacent the side windows of the vehicle. In the event of a specific type of accident, such as, for example, a side impact, the inflatable element inflates, thus extending down to cover the windows in the manner of a curtain. Typically the opposed ends of the lower edge of the inflatable element are secured to mounting points, optionally with the use of straps, and, as the inflatable element inflates, so the length of the lower edge of the inflatable element reduces, thus creating a line of tension extending between the two anchoring points. Thus the inflatable element is held securely in position, minimising the risk of any part of an occupant emerging through a window during the accident.
It has been proposed to provide certain regions of the inflatable element which do not actually inflate in order to minimise the quantity of gas needed to inflate the inflatable element, and also to ensure that the inflatable element can be inflated in the relatively brief period of time that is typically available in a side impact situation.
While many designs of inflatable curtain have been produced in recent years for use in different types of motor vehicle. It has been found, especially in connection with inflatable elements designed for use in vehicles having a substantial length, such as vehicles of xe2x80x9cMPVxe2x80x9d type, where the inflatable element can extend from an xe2x80x9cAxe2x80x9d-Post to a xe2x80x9cDxe2x80x9d-Post that, excessive tension can occur in the lower edge of the inflatable curtain, thus distorting the inflatable curtain in an undesirable manner.
The present invention seeks to provide an improved air-bag arrangement.
According to this invention there is provided an air-bag arrangement in the form of an inflatable curtain adapted to be mounted in a motor vehicle and adapted, when inflated, to extend adjacent the side windows of the motor vehicle, the air-bag arrangement including an inflatable element having an upper edge provided with means to mount the upper edge to the roof of a motor vehicle, and an opposed lower edge, the opposed ends of the lower edge being provided with means to connect the said opposed ends to anchoring points within a motor vehicle, the lower edge of the inflatable element having between the anchoring points at least one inflatable region and at least one uninflatable region, the uninflatable region being provided with one or more apertures therein, the arrangement being such that, on inflation of the inflatable element, the width of the or each aperture will increase to moderate the tension generated between the said anchoring points by the inflation of the inflatable region.
Preferably there are at least two inflatable regions separated by a said uninflatable region.
Conveniently a gas flow duct is defined adjacent the upper edge of the inflatable element, and the gas flow duct communicates with the inflatable regions, each of which extends from the gas flow duct towards the lower edge of the inflatable element, at least one inflatable region being divided into a plurality of inflatable cells by means of seams provided within each inflatable region.
In one embodiment of the invention the inflatable element has three inflatable regions, and two uninflatable regions which separate the three inflatable regions, each of the uninflatable regions being provided with said apertures.
In a further embodiment of the invention the inflatable element has an uninflatable region located between an inflatable part of the lower edge and at least one of the anchoring points.
Conveniently respective uninflatable regions are located between a main part of the lower edge and each of the two anchoring points.
Preferably the or each uninflatable region is provided with a plurality of apertures.
Conveniently the plurality of apertures are provided in a plurality of rows of apertures, at least one row of apertures extending adjacent and parallel with the lower edge of the inflatable element, and another row of apertures extending at a location between the lower-most row of apertures and the upper edge of the inflatable element.
Advantageously the number of apertures present in the lower row of apertures is greater than the number of apertures present in the upper row of apertures.
The apertures may be oval apertures or may be zig-zag apertures.
The invention also relates to a method of making the inflatable element as described above in which the method comprises the steps of using a one-piece weaving process to fabricate the inflatable curtain, and a laser cutting process to cut the or each aperture.